Semi-analytical Solutions on Seepage Field of Twin Tunnels

Based on the governing equation of steady-state seepage, the semi-analytical solutions of seepage field of twin tunnels considering the effect of lining is derived rigorously using the technique of conformal mapping. These solutions can provide the values of total hydraulic head at an arbitrary point in the seepage field and the tunnel water ingress. Discussion is given about the effects of the tunnel distance on the distribution of the total hydraulic head outside the twin tunnels and the tunnel water ingress. It is found that simplifying the twin tunnels as a single tunnel in analysis could overestimate the hydraulic head around tunnels and the tunnel water ingress.